Last 4-5 years I have been hearing a clunking sound from rear of the truck.
This noise only happens when I stop at a red light or stop sign and then proceed across the street.
The truck has been lube, rear-in replaced , bearings greased as well as the pinion rod(?) They also checked the brakes and tires.
Mechanic technicians are not sure what it is. They emphasize me not to stop to quickly. Whatever happens during the braking something in that area rolls up and then releases to make that noise
I have a similar problem on my Ford truck. First step is to make sure the u-joints have no play. They should have absolutely no play at all that you can notice by applying twisting force with your hands.
After that, as posted above, lubing the slip joint definitely helps, but doesn’t entirely solve it in my case. I don’t remove the drive shaft though, there’s a lube fitting on slip joint so I just use that. I think it might work a little better to remove the drive shaft for this, so I’d have access to the entire length of the spline. I’ll try that next time. The other thing that seems to help is to add some friction modifier to the differential fluid. This makes the clutches in the limited slip differential more slippery. Otherwise those clutches can grab and cause clunking noises.
Other potential causes, it sounds you’ve probably already addressed those: play between the pinion and the ring gear; play between the rear axles and the differential side gears. Play in the transmission or transfer case (if 4WD) could cause it too.
Another less likely possibility, the entire rear axel is subjected to a twisting force during accelerations and decelerations. The truck’s designers know about this of course, and counteract it w/various methods. So perhaps one of those methods isn’t working b/c something fell off or is loose that otherwise would counteract the twisting force. The link below might be helpful.
Mine would clunk just like yours. The other day I used a screw driver and a hammer and spread apart the leafs and installed some rubber pieces I had cut to stop the metal (leafs) from slapping together. All the noise is gone and it rides as smooth as a new truck. Hope this helps.
Hopefully OP @martindoug1949_176703 will return and let us know of any progress. Rear end clunks on trucks, esp when stopping/starting, seem a pretty common complaint. Caller on fairly recent Car Talk podcast asked the same question, Ray suggested to try lubing the end of leaf springs as I recall.
I’d be a little worried that sort of modification might affect the suspension system’s handling. If trying that idea, suggest to drive extra slowly and carefully until proved ok by driving experience. Probably ok, but best to error on the side of safety.